167 research outputs found
Functional outcome of arthroscopic reconstruction of anterior cruciate ligament tear using peroneus longus tendon autograft
Background: The objective of the study was to evaluate the functional outcome of arthroscopic reconstruction of ACL tear using triple layered PLT autograft and to study its effect on ankle stability.Methods: The study included 25 patients. The range of age was 18-42 years. Pre-op clinical tests and MRI was done to confirm tear. Reconstruction was done arthroscopically. Physiotheraphy protocol was fixed for all patients. Final outcome was assessed at 6 months using IKDC score and ankle stability was assessed by grading muscle power (MRC grading) with the normal side as control.Results: IKDC score was normal or near normal in 21 patients and only 4 patients were rated as abnormal or severely abnormal. Mean IKDC Score was 83.53. Stability of the ACL was assessed using the Lachman test: normal in 18 cases (72%), 1+ laxity in 5 cases (20%), 2+ and 3+ in 1 case (4%) each. Pivot shift was negative in 15 cases (60%), Pivot glide was seen in 9 cases (36%) and gross pivot shift was seen in 1 patient. Partial meniscectomy of the medial meniscus was performed in 5 patients. No patient experienced ankle dysfunction however 2 patients had pressure pain in the region of the graft harvest.Conclusions: PLT graft is similar to the native ACL both in terms of thickness and strength. It can be an appropriate autograft option for ACL reconstruction without compromising ankle function and avoiding potential complications of hamstring and BPTB autograft obtained from the knee region
When Can You Fold a Map?
We explore the following problem: given a collection of creases on a piece of
paper, each assigned a folding direction of mountain or valley, is there a flat
folding by a sequence of simple folds? There are several models of simple
folds; the simplest one-layer simple fold rotates a portion of paper about a
crease in the paper by +-180 degrees. We first consider the analogous questions
in one dimension lower -- bending a segment into a flat object -- which lead to
interesting problems on strings. We develop efficient algorithms for the
recognition of simply foldable 1D crease patterns, and reconstruction of a
sequence of simple folds. Indeed, we prove that a 1D crease pattern is
flat-foldable by any means precisely if it is by a sequence of one-layer simple
folds.
Next we explore simple foldability in two dimensions, and find a surprising
contrast: ``map'' folding and variants are polynomial, but slight
generalizations are NP-complete. Specifically, we develop a linear-time
algorithm for deciding foldability of an orthogonal crease pattern on a
rectangular piece of paper, and prove that it is (weakly) NP-complete to decide
foldability of (1) an orthogonal crease pattern on a orthogonal piece of paper,
(2) a crease pattern of axis-parallel and diagonal (45-degree) creases on a
square piece of paper, and (3) crease patterns without a mountain/valley
assignment.Comment: 24 pages, 19 figures. Version 3 includes several improvements thanks
to referees, including formal definitions of simple folds, more figures,
table summarizing results, new open problems, and additional reference
Clustered chimera states in delay coupled oscillator systems
We investigate "chimera" states in a ring of identical phase oscillators
coupled in a time-delayed and spatially non-local fashion. We find novel
"clustered chimera" states that have spatially distributed phase coherence
separated by incoherence with adjacent coherent regions in anti-phase. The
existence of such time-delay induced phase clustering is further supported
through solutions of a generalized functional self-consistency equation of the
mean field. Our results highlight an additional mechanism for cluster formation
that may find wider practical applications
Phosphoenolpyruvate carboxylase dentified as a key enzyme in erythrocytic Plasmodium falciparum carbon metabolism
Phospoenolpyruvate carboxylase (PEPC) is absent from humans but encoded in thePlasmodium falciparum genome, suggesting that PEPC has a parasite-specific function. To investigate its importance in P. falciparum, we generated a pepc null mutant (D10Δpepc), which was only achievable when malate, a reduction product of oxaloacetate, was added to the growth medium. D10Δpepc had a severe growth defect in vitro, which was partially reversed by addition of malate or fumarate, suggesting that pepc may be essential in vivo. Targeted metabolomics using 13C-U-D-glucose and 13C-bicarbonate showed that the conversion of glycolytically-derived PEP into malate, fumarate, aspartate and citrate was abolished in D10Δpepc and that pentose phosphate pathway metabolites and glycerol 3-phosphate were present at increased levels. In contrast, metabolism of the carbon skeleton of 13C,15N-U-glutamine was similar in both parasite lines, although the flux was lower in D10Δpepc; it also confirmed the operation of a complete forward TCA cycle in the wild type parasite. Overall, these data confirm the CO2 fixing activity of PEPC and suggest that it provides metabolites essential for TCA cycle anaplerosis and the maintenance of cytosolic and mitochondrial redox balance. Moreover, these findings imply that PEPC may be an exploitable target for future drug discovery
Sparse Gamma Rhythms Arising through Clustering in Adapting Neuronal Networks
Gamma rhythms (30–100 Hz) are an extensively studied synchronous brain state responsible for a number of sensory, memory, and motor processes. Experimental evidence suggests that fast-spiking interneurons are responsible for carrying the high frequency components of the rhythm, while regular-spiking pyramidal neurons fire sparsely. We propose that a combination of spike frequency adaptation and global inhibition may be responsible for this behavior. Excitatory neurons form several clusters that fire every few cycles of the fast oscillation. This is first shown in a detailed biophysical network model and then analyzed thoroughly in an idealized model. We exploit the fact that the timescale of adaptation is much slower than that of the other variables. Singular perturbation theory is used to derive an approximate periodic solution for a single spiking unit. This is then used to predict the relationship between the number of clusters arising spontaneously in the network as it relates to the adaptation time constant. We compare this to a complementary analysis that employs a weak coupling assumption to predict the first Fourier mode to destabilize from the incoherent state of an associated phase model as the external noise is reduced. Both approaches predict the same scaling of cluster number with respect to the adaptation time constant, which is corroborated in numerical simulations of the full system. Thus, we develop several testable predictions regarding the formation and characteristics of gamma rhythms with sparsely firing excitatory neurons
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